After watching this
Thinkpad Tablet 10 video, I keep thinking that the 10" Surface Pros were a flawed from factor and it really should be replaced with a Baytrail unit that works as full Win 8.1 device that is thin and light without fan. That TPT10 is a 1.3 lbs device. Very much a "tablet" size and weight. Add the new infinite angle kickstand to that, and I think it would eliminate most of shitty criticism from the journos that never really gave credit to Core i5 power in such form factor and clamored for more tablet like size and weight.
And maybe this move to 12" for SP3 is part of that realization. You give them a bigger form factor for those who still want Core i5 power, and bring down the 10" down to more tablet like weight.
And then the 8" form factor can be relegated to RT-esque functionality that does not give you desktop at all. RT only retained desktop for Office anyways, so when Office goes to touch interface, voila, no more RT with desktop mess. Keep desktop for full Windows 8.1 on 10" an 12" form factors.